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Design selection electromagnetic flowmeter and orifice flowmeter note introduction

Industrial automation is the core technology of industrialization development and industrial structure optimization and upgrading in China. In the industrial process automation control system, electromagnetic flowmeter and orifice flowmeter play a very important role as the instrument tool for the detection and measurement of medium flow. For example, in a circulating electric heating system, the necessary condition for electric heater to drive is that there must be medium flow, and the electric heater can work. Otherwise, the electric heater is in an air-burning state, and it takes only a few seconds to burn the equipment. Therefore, the design of the electric heating system not only needs to design the temperature interlocking device of the electric heater body to prevent dry burning, but also design a flow interlocking device at the entrance of the electric heater.

The flowmeters produced by each instrument manufacturer have their own product features. The flowmeters produced by Kailiu Instrument Technology Co., Ltd. are stable in quality and leading in technology, and have won the favor of customers. The following is a sample of the products produced by Kailiu Instrument Technology Co., Ltd., in the design of the industrial process automation control system, the design of the electromagnetic flowmeter and orifice flowmeter design needs to pay attention to:

First, the applicability of the media. The electromagnetic flowmeter can measure liquid media such as acid, alkali, salt solution, water, sewage, corrosive liquid, mud, etc., and is not suitable for gas. Orifice flowmeters are suitable for a wide range of media than electromagnetic flowmeters. They can measure not only liquids, but also single-phase media such as gases and vapors. Some mixed-phase media are also suitable.

Second, apply pressure and nominal pipe diameter. The applicable pressure of the electromagnetic flowmeter is within 10MPa, and the nominal diameter is between DN15-DN3000, which can be applied to the large buckle diameter. Orifice flowmeter is suitable for large pressure, the maximum can withstand static pressure 40MPa, suitable for the nominal diameter of the electromagnetic flowmeter is narrow, in DN10-DN1600, the large diameter pipe diameter exceeding DN1600 is not applicable.

Again, the pressure is lost. The orifice flowmeter measures the flow rate from the tube hole and the acute angle of the inner hole, and the pressure loss is large after the medium passes through the orifice flowmeter. The electromagnetic flowmeter is measured by Faraday electromagnetic induction, and the pressure loss is small and almost negligible. In the system design, the pressure loss (pressure drop) of each equipment is a very important parameter, which determines the working capacity and selection of the circulating pump (fan) in the system. If the pressure loss of each equipment in the system is large, it needs The larger capacity of the circulating pump (fan) increases the cost invisibly. Especially in some systems, due to the importance of the performance of the circulating pump (fan), the imported equipment is often used, and the cost may be much higher than that of a certain equipment. Therefore, in order to ensure the economical design of the whole system, the pressure loss becomes One of the important design considerations for each device in the system.

Finally, install the space. As a single meter, the electromagnetic flowmeter and the orifice flowmeter occupy the same installation space, but for the use conditions of the instrument, the electromagnetic flowmeter has lower requirements for the straight pipeline, and the orifice flowmeter has high requirements for the straight pipeline. Generally, the length of the meter inlet is not less than 10 times the length of the nominal pipe diameter and the length of the meter outlet is not less than 5 times the nominal pipe diameter. This requirement is huge for installation of instruments, especially for large diameter pipes. When designing a flowmeter, the designer must fully consider the installation space requirements of the overall structural design of the system.

After comparison, the electromagnetic flowmeter and the tube orifice flowmeter each have their own scope of application, advantages and disadvantages, the designer must integrate all aspects, design and select the most suitable instrument.

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